National and Subnational estimates for the United States of America

Identifying changes in the reproduction number, rate of spread, and doubling time during the course of the COVID-19 outbreak whilst accounting for potential biases due to delays in case reporting both nationally and subnationally in the United States of America. These results are impacted by changes in testing effort, increases and decreases in testing effort will increase and decrease reproduction number estimates respectively (see Methods for further explanation).

Table of Contents


Using data available up to the: 2020-04-23

Note that it takes time for infection to cause symptoms, to get tested for SARS-CoV-2 infection, for a positive test to return and ultimately to enter the case data presented here. In other words, today’s case data are only informative of new infections about two weeks ago. This is reflected in the plots below, which are by date of infection.

Expected daily confirmed cases by region


Figure 1: The results of the latest reproduction number estimates (based on estimated confirmed cases with a date of infection on the 2020-04-12) in the United States of America, stratified by state, can be summarised by whether confirmed cases are likely increasing or decreasing. This represents the strength of the evidence that the reproduction number in each region is greater than or less than 1, respectively (see the methods for details). Regions with fewer than 40 confirmed cases reported on a single day are not included in the analysis (light grey).

National summary

Summary (estimates as of the 2020-04-12)

Table 1: Latest estimates (as of the 2020-04-12) of the number of confirmed cases by date of infection, the expected change in daily confirmed cases, the effective reproduction number, the doubling time, and the adjusted R-squared of the exponential fit. The mean and 90% credible interval is shown for each numeric estimate.
Estimate
New confirmed cases by infection date 30853 (30184 – 31544)
Expected change in daily cases Increasing
Effective reproduction no. 1 (1 – 1)
Doubling time (days) 87 (58 – 170)
Adjusted R-squared 0.73 (0.49 – 0.95)

Reported confirmed cases, their estimated date of infection, and time-varying reproduction number estimates


Figure 2: A.) Confirmed cases by date of report (bars) and their estimated date of infection. B.) Time-varying estimate of the effective reproduction number. Light ribbon = 90% credible interval; dark ribbon = the 50% credible interval. Estimates are shown until the 2020-04-12.Dark grey ribbon = 50% credible interval. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence.

Time-varying rate of growth and doubling time


Figure 3: A.) Time-varying estimate of the rate of growth, B.) Time-varying estimate of the doubling time in days (note that when the rate of growth is negative the doubling time is assumed to be infinite), C.) The adjusted R-squared estimates indicating the goodness of fit of the exponential regression model (with values closer to 1 indicating a better fit). Estimates are shown until the 2020-04-12. Light ribbon = 90% credible interval; dark ribbon = the 50% credible interval. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence.

Regional Breakdown

Data availability

Limitations

Summary of latest reproduction number and confirmed case count estimates by date of infection


Figure 4: Confirmed cases with date of infection on the 2020-04-12 and the time-varying estimate of the effective reproduction number (light bar = 90% credible interval; dark bar = the 50% credible interval.). Regions are ordered by the number of expected daily confirmed cases and shaded based on the expected change in daily confirmed cases. The dotted line indicates the target value of 1 for the effective reproduction no. required for control and a single case required for elimination.

Reproduction numbers over time in the six regions expected to have the most new confirmed cases


Figure 5: Time-varying estimate of the effective reproduction number (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in the regions expected to have the highest number of new confirmed cases. Estimates are shown up to the 2020-04-12. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The dotted line indicates the target value of 1 for the effective reproduction no. required for control.

Reported confirmed cases and their estimated date of infection in the six regions expected to have the most new confirmed cases


Figure 6: Confirmed cases by date of report (bars) and their estimated date of infection (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in the regions expected to have the highest number of new confirmed cases. Estimates are shown up to the 2020-04-12. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence.

Reproduction numbers over time in all regions


Figure 7: Time-varying estimate of the effective reproduction number (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in all regions. Estimates are shown up to the 2020-04-12. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The dotted line indicates the target value of 1 for the effective reproduction no. required for control.

Reported confirmed cases and their estimated date of infection in all regions

Figure 8: Confirmed cases by date of report (bars) and their estimated date of infection (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in all regions. Estimates are shown up to the 2020-04-12. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence.

Latest estimates (as of the 2020-04-12)

Table 2: Latest estimates (as of the 2020-04-12) of the number of confirmed cases by date of infection, the effective reproduction number, and the doubling time in each region. The mean and 90% credible interval is shown.
State New confirmed cases by infection date Expected change in daily cases Effective reproduction no. Doubling time (days)
Alabama 199 (140 – 245) Unsure 1 (0.8 – 1.2) -62 (20 – Inf)
Arizona 193 (133 – 249) Unsure 1 (0.8 – 1.2) 110 (13 – Inf)
Arkansas 158 (110 – 206) Increasing 1.5 (1.1 – 1.8) 9.2 (5.2 – 44)
California 1664 (1496 – 1808) Increasing 1.2 (1.1 – 1.3) 20 (14 – 36)
Colorado 350 (279 – 420) Unsure 1 (0.9 – 1.1) -500 (22 – Inf)
Connecticut 924 (808 – 1034) Unsure 1 (0.9 – 1.1) 120 (27 – Inf)
Delaware 161 (107 – 207) Unsure 1.1 (0.9 – 1.4) 39 (9.8 – Inf)
District of Columbia 158 (106 – 212) Likely increasing 1.1 (0.9 – 1.4) 25 (8.4 – Inf)
Florida 819 (697 – 910) Likely decreasing 0.9 (0.8 – 1) -58 (74 – Inf)
Georgia 690 (589 – 787) Likely decreasing 0.9 (0.8 – 1) -110 (38 – Inf)
Guam 23 (1 – 42) Unsure 0.9 (0.3 – 1.5) -25 (4.6 – Inf)
Idaho 40 (8 – 68) Unsure 1.2 (0.6 – 1.9) 16 (3.8 – Inf)
Illinois 1381 (1238 – 1517) Unsure 1 (0.9 – 1.1) 250 (35 – Inf)
Indiana 488 (409 – 575) Unsure 1 (0.9 – 1.2) 67 (18 – Inf)
Iowa 340 (262 – 404) Increasing 1.5 (1.2 – 1.7) 8.3 (5.7 – 15)
Kansas 115 (62 – 169) Likely increasing 1.2 (0.9 – 1.6) 16 (6 – Inf)
Kentucky 170 (105 – 226) Likely increasing 1.2 (0.9 – 1.4) 22 (7.9 – Inf)
Louisiana 446 (367 – 529) Decreasing 0.9 (0.7 – 1) -39 (62 – Inf)
Maine 34 (1 – 63) Unsure 1 (0.4 – 1.6) -15 (5.3 – Inf)
Maryland 659 (561 – 755) Unsure 1 (0.9 – 1.1) 270 (25 – Inf)
Massachusetts 1694 (1513 – 1838) Likely decreasing 1 (0.9 – 1) -83 (92 – Inf)
Michigan 757 (646 – 845) Decreasing 0.8 (0.7 – 0.9) -18 (Inf – Inf)
Minnesota 139 (78 – 194) Likely increasing 1.2 (0.8 – 1.5) 22 (7.2 – Inf)
Mississippi 237 (168 – 293) Unsure 1.1 (0.9 – 1.3) 36 (11 – Inf)
Missouri 168 (103 – 216) Likely decreasing 0.9 (0.7 – 1.1) -21 (37 – Inf)
Nebraska 145 (83 – 207) Increasing 1.3 (1 – 1.7) 12 (5.5 – Inf)
Nevada 119 (65 – 166) Unsure 1 (0.7 – 1.2) -120 (12 – Inf)
New Hampshire 68 (26 – 105) Unsure 1.1 (0.7 – 1.5) 61 (6.6 – Inf)
New Jersey 3514 (3283 – 3723) Unsure 1 (1 – 1.1) 150 (47 – Inf)
New Mexico 102 (60 – 148) Unsure 1.1 (0.8 – 1.4) 43 (8.1 – Inf)
New York 5383 (5084 – 5659) Decreasing 0.8 (0.7 – 0.8) -14 (Inf – Inf)
North Carolina 282 (201 – 344) Unsure 1 (0.9 – 1.2) 64 (13 – Inf)
North Dakota 70 (25 – 118) Likely increasing 1.6 (0.9 – 2.2) 7.4 (3.4 – Inf)
Ohio 1123 (988 – 1235) Increasing 1.4 (1.2 – 1.5) 9.1 (7.1 – 12)
Oklahoma 96 (52 – 132) Unsure 1 (0.7 – 1.3) -150 (11 – Inf)
Oregon 69 (27 – 107) Unsure 1.1 (0.7 – 1.5) 45 (6.3 – Inf)
Pennsylvania 1310 (1168 – 1437) Likely decreasing 1 (0.9 – 1) -120 (60 – Inf)
Puerto Rico 73 (31 – 111) Likely increasing 1.3 (0.8 – 1.7) 17 (5.1 – Inf)
Rhode Island 338 (266 – 396) Likely increasing 1.1 (0.9 – 1.2) 55 (15 – Inf)
South Carolina 136 (85 – 181) Unsure 0.9 (0.7 – 1.1) -71 (15 – Inf)
South Dakota 96 (47 – 141) Unsure 0.9 (0.6 – 1.2) -16 (21 – Inf)
Tennessee 240 (177 – 296) Unsure 1 (0.8 – 1.2) 260 (17 – Inf)
Texas 734 (619 – 830) Likely decreasing 0.9 (0.8 – 1) -71 (51 – Inf)
Utah 135 (74 – 185) Unsure 1.1 (0.8 – 1.4) 23 (7.3 – Inf)
Vermont 63 (0 – 143) Unsure 2.2 (0.2 – 4.1) 9.8 (1.8 – Inf)
Virginia 539 (444 – 616) Increasing 1.1 (1 – 1.3) 25 (13 – Inf)
Washington 234 (154 – 299) Unsure 1 (0.8 – 1.2) 50 (11 – Inf)
West Virginia 57 (17 – 96) Unsure 1.3 (0.7 – 1.8) 17 (4.4 – Inf)
Wisconsin 154 (95 – 215) Unsure 1 (0.8 – 1.3) 75 (10 – Inf)

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